Every guild has that issue.
Key that those guilds do is have access to a larger recruitment base so they can refill/reload easier. They also have players that are willing to sit on progression weeks unless they are needed where in other guilds that'd be drama/.
I can't speak for every guild you listed, but I can say that in the last six months we've had 12 applications.
If that's the larger recruitment base then ...we are all collectively fuct.